The North's First Minister, Mr David Trimble, last night said the rearrest and return to prison of Shankill UDA commander Johnny Adair was akin to internment without trial.
Although he did not condemn the move, he said similar action had not been taken against the "Real IRA" and others engaged in violence in the North.
He stressed the law must be applied "in an even-handed manner and it should apply across the board, not just with regards to a particular individual with a particular background".
Mr Trimble was speaking at a press conference at Stormont where he appealed for an end to the loyalist feud and called for "firm and decisive action" from the British government and the RUC.
The feud has continued to escalate with violence spreading to Carrickfergus, Co Antrim, where 32 houses were damaged in tit-for-tat attacks by both the UVF and UDA early yesterday.
British soldiers were last night ordered back on to the streets of the town to prevent further disturbances. RUC Assistant Chief Constable Bill Stewart described the move as "regrettable but, in my view, necessary".
According to figures released yesterday, 150 families - mostly from the Shankill area in Belfast - have asked the Housing Executive to be rehoused since the feud began 12 days ago.
Mr Trimble will discuss the security situation with senior RUC officers in Belfast today.
Last week, Mr Mandelson revoked Johnny Adair's early release licence and he was sent to Maghaberry jail. Speaking about that decision, Mr Trimble said that while his rearrest might be "fine", the law should be applied in an even-handed manner. Although he had previously supported selective internment, it must be employed as a "broad concept", he said.
The Ulster Democratic Party, the UDA's political wing, has been the only political party to condemn Adair's arrest. It has challenged the RUC to charge him if there is evidence of his involvement in illegal activities.
It is understood that while there is considerable intelligence information on Adair, no hard evidence - that would stand up in court - exists.
Mr John White of the UDP said he agreed the violence must end: "It is seriously damaging the whole fabric of the loyalist community." He called for a truce but claimed it was notable that the UVF's political wing, the Progressive Unionist Party, was not making similar appeals.
So far, the feud has claimed three lives. Meanwhile, Charlene Daly (11) is recovering in hospital after a UVF gun attack on her family's home in Coleraine on Monday.